Can Type 2 Diabetes Be Corrected with Bariatric Surgery

The prevalence of type 2 diabetes and obesity has increasingly grown in tandem worldwide.

As of today, the most effective treatment for severe obesity that can achieve long term weight loss is bariatric surgery.³ Particularly for those who have tried other ways to lose weight, such as dieting and exercising. Given the high association between these 2 pathologies (obesity and diabetes), the concept of ‘diabesity’ has been utilized to describe patients who are severely obese and diabetic at the same time.⁴ “The term diabesity is the unification of the words ‘diabetes’, referring to type 2, and ‘obesity’. It is a wonderful word because it is at once able to convey that they are truly one and the same disease. It is incredibly descriptive and evocative in the same way as the word ‘fugly’”, said Dr. Jason Fung, MD, a nephrologist and a world-leading expert on intermittent fasting and LCHF, especially for treating people with type 2 diabetes⁵ Of all the patients who undergo bariatric surgery, roughly 30% correspond to diabetes patients.

Type 2 diabetes mellitus (T2D) is associated with serious health consequences. The development of T2D has a strong association with obesity, sedentary lifestyle, genetic factors and other associations of diabetes.⁶ Faced with this problem, bariatric surgery has evolved as the treatment that produces a greater decrease in body weight long-term. Moreover, it is postulated that bariatric surgery currently may have a beneficial effect in improving pharmaceutical treatment and even promoting diabetes remission in obese patients.⁷

The surgical technique that offers the most benefit has been Roux-en-Y gastric bypass, which is why it’s the technique of choice of many obese and diabetic patients.

A meta-analysis reported that gastric bypass presented a remission of diabetes type 2 of close to 60 % of cases, while a gastric band has allowed remissions of 29% of cases in the first year.

“What we found is that the secret for the cure of diabetes after gastric bypass lies in the intestine. The key message is that after gastric bypass the intestine becomes the most important tissue for glucose use and this decreases blood sugar levels,” said Dr. Nicholas Stylopoulos, principal investigator at the Division of Endocrinology at Children’s Hospital Boston and Boston Medical School, in an interview with Healthline. ¹⁰

A diminution of glycemic levels, basal insulinemia, and glycosylated hemoglobin has also been observed. Thus, many patients can lower the use of oral hypoglycemic sulfonamides to fight diabetes.

A group of metabolic intestinal hormones, called incretins, play a central role in the remission of diabetes type II (along with weight loss and postoperative dieting). Incretins stimulate the secretion of postprandial insulin and are associated to the physiological mechanisms produced as a consequence of gastric bypass procedures that regulate or improve glycemic levels.

The Role of Bariatric Surgery

Weight loss procedures have permitted an important reduction of body weight in the long run, unlike other types of medical treatment. There are different surgical techniques at play: ¹¹

1. Restrictive
2. Malabsorptive
3. Mixed

The first gastric surgery that reported an improved control of diabetes took place in 1955, but it wasn’t until 30 years later that the procedure was considered clinically important. In the 1980s, it was observed that gastric bypass surgery is associated to improved glycemic ¹² and insulinemic levels of around 77% – 97% during oral glucose tolerance tests. Today, bariatric surgery is recommended for patients who’s reiterated treatment plans have previously failed, present a BMI between 35 – 40 (or a BMI greater than 40, regardless of the presence of a chronic disease¹³), and have a medically relevant pathology whose prognosis is affected by obesity, such as arterial hypertension, diabetes, dyslipidemia, sleep apnea, or osteoarticular conditions. ¹⁴ The Roux-en-Y gastric bypass improves not only weight, but also ameliorates insulin resistance and improves glycemic levels.  

Surgical candidates should be rigorously evaluated by a medical team in order to ensure postoperative compliance and proper progression.

On the other hand, patients for whom bariatric surgery is contraindicated are those that suffer from:

• Cardiac insufficiency
• Severe respiratory insufficiency
• Psychiatric disorders, such as psychosis
• Inflammatory intestinal diseases
• Hepatic insufficiency
• Pancreatic insufficiency
• Drugs or alcohol abuse problems
• Malabsorption syndrome

 Complications of Bariatric Surgery

Although the rate of complications is relatively low (major complications occur in less than 10% of cases), they can cause significant disability. ¹⁵ Surgeries whose outcome adversely affected the patient have provoked claims of mal praxis, which are particularly problematic for bariatric surgery centers. For these reasons, performing surgeons should be well prepared and possess the exceptional technical skills required to handle complications when they occur.

Physiological reserves are significantly reduced in obese patients (and by extension, patients who seek bariatric surgery). As a result of their excessive mass, their bodies do not express possible complications clearly. For example, in people with normal BMI, peritonitis symptoms include tachycardia, fever, abdominal pain, and a high WBC reading from a CBC (complete blood count) as a consequence of sepsis. However, obese patients may just show tachycardia (lacking fever and abdominal pain) despite possible sepsis. Of all likely manifestations of intra-abdominal sepsis, a BPM reading of more than 120 is the most reliable finding in obese patients. “Any sustained heart rate reaching 120 beats per minute should be a red flag to check for a potential leak,” according to James A. Madura II, MD, director of the bariatric surgery program at the Mayo Clinic in Scottsdale, Arizona. ¹⁶ For this reason, when post-op bariatric surgery patients present any signs of tachycardia, the medical professionals in charge should assume that an intraabdominal abscess or an anastomotic leak may exist.¹⁷ Imaging studies for the purpose of confirming such a suspicion are difficult to observe and tend to be less reliable due to the size of obese patients.

Like any surgery, bariatric procedures carry a certain degree of risk for possible postoperative complications, especially the first 2 months after surgery. Common complications that have been observed during this time are embolisms, infection of the surgical wound, incisional hernias, and fistulas. “During the first few weeks after surgery, pulmonary embolism and a gastric leak from the anastomosis lead the list of life-threatening complications,” Dr. Madura said. ¹⁸  A gastric bypass, specifically, can cause complications, such as dehiscence of the anastomosis, intestinal obstruction, dumping syndrome, calcium deficiency, anemia, and vomiting. ¹⁹

On the other hand, possible complications after a vertical sleeve gastrectomy are minor when compared to a Roux-en-Y. However, they can present secondary vomiting (from overeating), intestinal stenosis, ulcers, intestinal obstruction, and pouch dilation. ²⁰

After 2 months, a different set of complications can begin to appear. These include nutritional, hepatobiliary, and dermatological symptoms. Bariatric surgery can produce nutritional alterations as a result of anatomical and physiological changes to the digestive system. As a consequence, this procedure will produce a change in the quantity and quality of the diet, which in turn triggers the development of vitamin and mineral deficiencies. ²² In general, it’s very difficult for patients to consume over 1,000 calories a day after the first 2 months post-surgery, which doesn’t cover the daily requirements of vitamins and minerals.²³ 

Post-Op: Physiological Changes 

Various studies have detailed the intestinal hormonal changes that take place, especially that of incretins. These are vital to the homeostasis of glucose and effects on satiety. Among them we can highlight glucagon-like peptide-1 (GLP-1) and gastro-inhibitory peptide (GIP), both of which have demonstrated improvement of insulin secretion in diabetes type II patients. ²⁴ GIP is secreted by the K cells of the proximal small intestine, whereas GLP-1 is secreted by L cells of the distal portion of the small intestine. ²⁵

According to a study by Marianne Gosch C. and Pamela Rojas M., called ‘Can Type 2 Diabetes Be Corrected Via Bariatric Surgery?’, they state “In obese and diabetic patients, it is postulated that a chronic adaptation of pancreatic beta cells leads to a greater secretion of insulin, which presents a degree of impairment of the same to respond against sharp nutritional changes, such as the type of fasting required by post-operative patients. This explains the hypoglycemic episodes reported in many cases.” ²⁶

Weight loss procedures, such as liposuction, have not demonstrated a relationship with an increase of incretin production. Rather, it is gastric bypass surgery itself that is responsible for the elevated secretion of GLP-1.  ²⁷

One hypothesis suggests that higher production of incretins is triggered by exposure of the small intestine to nutrients. After an ileal interposition surgery in rats, they presented a persistent increase of GLP-1 in plasma, as well as a heightened expression of mRNA for proglucagon in the ileum.²⁸

Another hypothesis is called the ‘foregut’ hypothesis, which proposes excluding the proximal jejunum and the duodenum in the hopes it will inhibit a signal that promotes insulin resistance. This inhibition-by-exclusion is what happens after a gastric bypass procedure; it results in improvement of the body’s sensitivity to insulin, normalized glycemia levels during fasting, and better results from an oral glucose tolerance test (OGTT). ²⁹

In a study of rats published in the Annals of Surgery (November, 2006), a group of scientists attempted to demonstrate the differences between a duodenal-jejunal bypass (DJB) and a Roux-en-Y procedure with regards to their effects on the interaction of the small intestine with nutrients, and how this interaction triggers a cascade of insulin regulation mechanisms.³⁰ The rats that underwent a Roux-en-Y presented a better response to OGTT than the DJB group, although they were both helpful in controlling glycemia. Researchers concluded that anti-incretins produced in the proximal intestine can contribute to diabetes type II phenotype, while the exclusion of this portion would actually reduce the effects of diabetes. If there are more anti-incretins than incretins, it can result in hypoinsulinemia and an eventual shortage of pancreatic beta cells. Hence, this study successfully showed that the incretin system can be balanced out at the expense of the proximal segment of the small intestine by way of excluding it, which would explain the resolution of diabetes type II post-DJB. ³⁰

Different studies have described the improvement of insulin resistance in post-operatory patients who underwent metabolic surgery to achieve weight loss. ³¹ Given that adiposity is a determinant of insulin sensitivity, it was verified that weight loss indeed improves insulin tolerance.³²

Weight reduction also produces a diminution of proinflammatory cytokine markers, such as C reactive protein (CRP) and IL-6, as well as improving adiponectin levels (assuming significant weight loss)³³.  Higher adiponectin levels mean better sensitivity to insulin.³⁴ 

We should also highlight the importance of diabetes type II evolution, since the normalization of the effect of incretins can persist for a whole year after surgery. Insulin secretion in diabetes patients can be very variable, depending on factors such as age, family history, current illness duration, and level of insulin resistance. For obese patients over the age of 40 who are diabetic, the resolution of their condition is rare, since it appears that the pathogenesis of hyperglycemia in morbid obesity compared to moderate obesity is different. ³⁵

In a study led by Hall, it is suggested that the evolution of diabetes of 10 years or more, with bad glycemic control, would present poor remission rates. Predicting factors for successful remission are weight loss of at least 30% in 6 months post-op and a short duration of diabetes pre-op. ³⁶ However, it has been observed that diabetes patients who underwent metabolic surgery and showed improvement of their glycemic levels have also presented a recurrence of diabetes. It is thought that regaining weight after bariatric surgery can be the main cause of this recurrence. This has been reported to be the case 2 or 3 years after surgery. Regaining weight can be favored by the loss of control of healthy food intake and with it the return of inappropriate dieting behaviors, or the consumption of foods that have a high glycemic index.

Nowadays, bariatric surgery represents an effective line of treatment against morbid obesity in conjunction with remission of diabetes type II. As a consequence, remission rates can be as high as 80% ³⁷when the improvement of glycemia is concomitant with significant weight loss. The procedure most associated with remission of ‘diabesity’ is the Roux-en-Y gastric bypass technique. ³⁸ There is still much left to investigate about the physiological changes that are produced post-op, since there are still discrepancies present in some studies. Furthermore, current research reveals that remission of diabetes 5 years after the operation decreases notably, for it is already being reported that diabetes type II can reoccur in up to 43% of cases. ³⁹

“Gastric surgery isn’t for everyone, but this evidence suggests that, once you have diabetes and are severely obese, you should strongly consider it, even though it doesn’t seem to be a cure for most patients,” said David E. Arterburn, MD, MPH, a general internist and principal investigator of the largest community-based study of long-term diabetes outcomes after bariatric surgery at Group Health Research Institute. ⁴⁰

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